Electrical switch



Juy 31959 A. J. coLLoTTA ELECTRICAL SWITCH Filed Oct. 9, 1957 m uhm@yarent 2,894,082 l Patented July 7, 1959 fire ELECTRICAL SWITCH AlbertJ. Collotta, Roslindale, Mass., assignor to Ark-Iles Switch Corporation,Watertown, Mass., a corporation of Massachusetts Application October 9,1957, Serial No. 689,150

1 Claim. (Cl. 200-44) This invention relates to rotary electrical switchmechanisms and more particularly to such mechanisms of the key-operatedtype.

Key-operated rotary electrical switches have many applications today forthe control of electrical circuits. A primary concern or requirement ofsuch a switch is that it be economical to produce while at the same timeproviding reliable operation, adequate safeguard against unauthorizedoperation, and indication of the status of the electrical circuitscontrolled thereby. The economic considerations in particular requirethat such a switch be capable of manufacture without close tolerances bymass production methods.

Accordingly, it is an object of the present invention to provide a novelkey-actuated rotary electrical switch, economical to manufacture andreliable in operation.

Another object of the invention is to provide a keyactuated switchhaving a key which may be removed from the switch actuating member onlyin one position, preferably the off position.

Another object of the invention is to provide a keyactuated switch whichprovides safeguards against the operation thereof without a suitablekey.

The invention provides a key-actuated rotary switch apparatus which maybe manufactured by economical mass production methods and one in whichthe components thereof are easily assembled into a switch mechanismwhich is operated by a key. A positioning member for the key supports itin such a manner that the key may be inserted and removed at a specificrotary position thereof. The supporting member further is designed tocoact with the key-housing and the switchactuating member to minimizethe possibilities of unauthorized operation of the switch.

Further objects and features of the invention will become apparent fromthe following description of a preferred embodiment thereof, togetherwith the accompanying drawings in which:

Fig. 1 is a side view of the preferred embodiment of the rotary switchwith the operating key in place;

Fig. 2 is a rear end view of the switch of Fig. 1;

Fig. 3 is an exploded view of the key-housing, the key-supporting disc,and the switch-actuating shaft, With the latter two being adapted to beassembled into the key housing;

Fig. 4 is a sectional side elevational View of the switch in Fig. 1 withthe actuating key inserted;

Fig. 5 is a sectional view along the lines 5 5 of Fig. 4;

Fig. 6 is a sectional View along the lines 6--6 of Fig. 4;

Fig. 7 is a sectional view, similar to the view of Fig. 4 with the keyand the switch mechanism rotated 180;

Fig. 8 is a sectional View along the lines 8 8 of Fig. 7; and

Fig. 9 is a sectional view of a modified construction of the switchactuating shaft.

The general configuration of the switch may be understood with referenceto Figures 1 and 2. The switch comprises a housing 10, a threadedmounting structure 12 and an actuating key 14. Electrical connectionsare made from a common central terminal 16 to one of three terminals 18,20, 22 by means of a wiper blade mounted on the rotor washer 24. Thefourth position of the switch provides an olf position. The terminalsare mounted on .an insulating member 26 and the insulating member issecured to the housing 10 by means of a plurality of bent-overprojections 28 extending from the housing. The switch mechanismconstruction is conventional, a spacer washer 30 being mounted betweenthe rotor washer 24 and a detent plate 32. A shaft 34, mounted withinthe threaded structure 12 and housing 10 coacts with the switchstructure to move the rotor washer 24 as determined by the rotation ofthe key 14.

The shaft 34 may be best seen in Fig. 3. It consists of a tubular memberhaving an extension 36 adapted to coact with appropriate slots` in thedetent Washer and rotor washer such that the switch elements move as aunit with the shaft 34. The tubular portion has a slot 38 cut in itwhich is adapted to receive the shank of the key 14. A hole 40 isdrilled in the tubular portion such that a coaxial recess is provided inthe rotatable sleeve 34. Thus, rotation of the shaft 34 is actuated by amember which operates against the edges of the slot 38 which areprovided only at the periphery of the shaft 34.

A disc 42 (best seen in Fig. 3) is inserted between the shaft 34 and aradial shoulder member 46 of the mountingV 12. The disc 42 is ofsufhcient thickness to provide support for the key and has a rectangularslot 44 of a width slightly greater than the thickness of the key 14 andof a depth slightly greater than the width of the key shank.

The mounting 12, as best seen in Fig. 3, has a bore of a diameter greatenough to receive shaft 34 and disc 42, with a radial shoulder 46providing a restricted cylindrical aperture and a slot 48 through*shoulder 46 in the upper portion thereof. Thus an appropriately shapedkey may be inserted through the aperture and slot 48 to rotate the shaftand switch mechanism. The slot 48 may be cut in the shoulder 46 at apoint other than twelve oclock if desired. Further, when it isadvantageous that the switch design permit the removal of the key 14 atmore than one position of the contacts, a plurality of appropriate slotsmay be cut in the shoulder 46.

The shape of an appropriate key 14 is shown in Fig. 4. The shank of thekey as seen in Fig. 4 has a lower surface cut away such that it willcoact with the washer 42. This lower surface rides on the bottom of theslot 44 when the key is inserted into the slot 38 in shaft 34. Bits 15and wards 17 are provided on the upper surface of the key 14, said bitscoacting with the edges of the slot 38 to rotate the shaft 34 as the key14 is turned.

With reference to Figs. 4 through 8, it will be seen that the key mustbe inserted into the switch in the position as shown in Fig. 4 whereinthe edge containing bits 15 and wards 17 passes through slot 48 inshoulder 46. The insertion of the key 14 is limited to the verticalposition by the position of slot 48 in shoulder 12 as the shoulder 46 isnot rotatable, and to the position of Fig. 4 rather than to the positionof Fig. 7 by the presence of flanges 50, 52 on the key handle adjacentthe shank and bits 15 on the shank. When the key is properly inserted asin Fig. 4, the shank of the key is supported by the washer 42 as may beseen in Fig. 6. In order to provide an indication of the position of theswitch, it is desirable that the key be removable only in one position.With the construction of the key-housing aperture as shown in Figs. 3and 5, it is obvious that the key could be removed only when in thepositions of Figs. 4 or 7. In order to provide positive identificationof the switch position, it is desirable that the key be removable onlyin the position as shown in Fig. 4. Provision of the disc 42 betweenthe/shaft. 34 and the housing aperture positions thekey `14 suchthat .it.cannot lbe removed in Aposition of Fig. 7,...even bytilting it. Thedisc .42, lin its inverted position, `assures the engagement of theAbits .15 .of the key. shank against the shouldermember 46 of thehousingll, thus preventing removal of the'key in this position.

.A modification of the switch actuating shaft .34 is shownin Fig. 9.YThe hole 40 in the embodiment shown in-Figs. 1-8-is drilled to atleasta depth .equal to the lengtho'f the slot'38. In order to obtainadditional surface area against which lthe key `14 may act, the hole .40may be drilled toa depth less than the length of theslot as Yshown inFig. V9. 'In this manner the key, Vin-,rotative action, contacts a slotedge '54 at the lperiphery of the drilledhole and in addition lthe slotedge T56 at the' base n of 'the hole.

VThus, a simple construction of a key-actuated rotary electrical switchsuitable for inexpensive mass production has been provided. VIn 'thepreferred embodiments, the key may be inserted andremoved .only when"the switch is in a given position (preferably .o` The disc, provided tosecurely position `'the key in the switch, also limits access totheactuating shaft by articles other than an appropriately designed key,thus reducing the likelihood of tampering by unauthorized operation Vofthe switch.

Theprineiples ofthe inventionhave `been. 'described in-relation to thepreferred-embodiments 'of a key-actuatedrotaryswitch. It willbevunderstood that'whilethere has been shown and described y*hereinpreferred embodiments, the yinvention is not 'intendedto be limited.thereby toall details thereof, anddeparturesfmaybe-rnade.therefrom-=within the spirit and scopeofthe'invention'as'set forth in the appended claim.

I claim:

A key-operated electrical switch including: a key barrel having a radialshoulder providing an aperture therein for receiving a at key with atleast one bit along one edge of the key shank, said aperture being acircular opening with a rectangular slot extending radially therefrom; acylindrical shaft vrotatably mounted Within said barrel and having'a-slot in one ,end adapted to receive said key, said shaft being adaptedat its other end to operate -upon a vrotary contact switching means;zand means 4for substantially 'preventing unauthorized foperation ofsaid switch including: in combination, a cylindrical cavity inthelcenter of said cylinder: axially coeXtensive with said slot .thereinand of sarne diameter as said circular opening in said vra'dialshoulder, said shaft thus being rotatable only by an instrument actingagainst edges of said slot provided only at the periphery of saidshaftyfandra disc rotatably mounted in-said barrel -between-saidshaft.and said radialshoulder-and lhavinga slot of rectangular cross-sectionof wwidth slightlyfgreater thanfthe-thick-ness i of said key -andofdepth .slightly greaternthantheswidth of the .key shank and bi,t:said

means thus requiring -an instrumentof predetermined shape to factupontheslot edge in the4 periphery. of said shaftnandsimultaneouslylimiting,.by operation ofthe slotted disc,'the` configuration` of theIinstrumenta which .is permitted tohave access-.to said shaft.

AReferences Cited in the le of this patent UNITED STATES PATENTS

